While many herbicides are immediately toxic to a large number of weed pests, it is known that the effect of many herbicides upon important plant cultivations is either non-selective or not adequately selective. Thus, many herbicides damage not only the weeds to be controlled, but to a greater or lesser extent, the desirable cultivated plants as well. This holds true for many herbicidal compounds which have been commercially successful and are commercially available. These herbicides include types such as triazines, phenylurea derivatives, halogenated acetanilides; carbamates, thiolcarbamates, thiolcarbamate sulfoxides, pyrrolidinones, benzonitriles, toluidine derivatives, and the like. Some examples of these compounds are described in U.S. Pat. Nos. 2,891,855, 2,913,237, 3,027,248, 3,037,853, 3,175,897, 3,185,720, 3,198,786, 3,257,190, 3,442,945, 3,582,314, 3,780,090, 3,952,056 and 4,110,105.
The side effect of injury to a cultivated crop by various herbicides is particularly inconvenient and unfortunate. When used in the recommended amounts in the soil to control broadleaf weeds and grasses, injury such as serious malformation or stunting of the crop plants results in loss of crop yield. The search continues for good selective herbicides.
Previous attempts are described to overcome this problem. The treatment of the crop seed with certain "hormonal" antagonistic agents to planting is described, see U.S. Pat. Nos. 3,131,509 and 3,564,768. The protective agents, as well as the herbicide, in these prior processes are largely specific to certain cultivated plant species or in the nature of the antagonistic agents. The prior antagonistic agents have not been notably successful. U.S. Pat. Nos. 4,021,224, 4,124,376, 4,137,070 and 3,989,503 relate to herbicide-antidote systems differing from previously cited patents. The aforementioned patents specifically exemplify and describe the treatment of seeds and soil treatment employing compounds of different chemical classes, not suggestive of the present invention.